Well if they're out poaching there's probably plenty of sticks around. I've always been handy with a blunt object. Their own shovel, perhaps? And there's a neat trick for pinning a person to the ground with a stick for a long time without hurting them; I don't remember the name of it, but you can just walk off and it's about as good as tying them to a small tree. I think that would be appropriate for this occasion. I'm not so worried about educating poachers as I am about delivering them to the proper authorities. The poachers already know about what they're doing, for the most part - I'm sure that they notice when the populations they cull from die out.